package com.easy;

/**
 * Created by Lxk on 2019/6/8.
 */
public class Solution709 {

    public String toLowerCase(String str) {
        if(str == null){
            return null;
        }
        StringBuffer sb = new StringBuffer();
        for(int i = 0;i < str.length(); i++){
            if(str.charAt(i)>='A'&&str.charAt(i)<='Z'){
                sb.append(Character.toLowerCase(str.charAt(i)));
            }else{
                sb.append(str.charAt(i));
            }
        }
        return sb.toString();
    }

}
